Author Topic: Uncapped headers  (Read 2413 times)

Offline Matt70

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Re: Uncapped headers
« Reply #15 on: August 10, 2016 - 08:14:14 am »
Now you have me thinking how I can do "uncapped" for my headers.  :bigsmile:

There are a few nice exhaust cut out products out there. Some even have bluetooth controls. Full exhaust to open headers with the push of a button :)
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Offline Plum6Pak

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Re: Uncapped headers
« Reply #16 on: August 10, 2016 - 01:09:22 pm »
There are a few nice exhaust cut out products out there. Some even have bluetooth controls. Full exhaust to open headers with the push of a button :)

This is what I used, very inexpensive way to go if you don't mind uncapping with the bolts. Very solid material, well constructed, awesome for the price!

https://www.summitracing.com/parts/sum-670137

Offline AussieMark

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Re: Uncapped headers
« Reply #17 on: September 25, 2016 - 03:36:40 am »
I've never understood the uncapped header thing every car I have ever driven without mufflers has been completely gutless with no bottom end power at all. The cars were driven to the exhaust shop with just headers installed then when the mufflers and tail pipes were installed you could feel the power increase so why would you want to uncap the exhaust? I think it has to do with the back pressure on the valves there is a condition known as over exhausting this is when the exhaust pipes are too large for the engine, turbo charged engines are not as sensitive to this as naturaly aspirated engines because the turbo provides some back pressure. I once drove a turbo charged car with no mufflers to the exhaust shop and on the way back you could feel the power increase with the full exhaust system fitted. Even my 2 stoke motocross bikes are hopeless with the muffler removed so I feel any engine will produce maximum power with the correct exhaust system connected I have even heard the exhaust valves can be damaged without the correct amount of back pressure.


Offline turbostang7

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Re: Uncapped headers
« Reply #18 on: September 25, 2016 - 07:23:51 am »
Comparing a 2 stroke to a 4 stroke is like apples and oranges, the two stroke needs the exhaust on it in order to create a scavenging effect to get the exhaust out.
While it is true that some exhaust is better than open headers (think header collector extensions on drag cars), I don't buy that mufflers need to be installed in order to get the most power out of the combo. if that was the case then every racecar in the world would have mufflers installed.

there is a video on YouTube that they tested this old myth about back pressure and exhaust. with a full exhaust they lost power from the tuned dyno headers and the extensions.
https://www.youtube.com/watch?v=rTlHEOE2Zp4
https://www.youtube.com/watch?v=_PVXvHkr-Vs
https://www.youtube.com/watch?v=azPKIjxmmdU
these are pretty interesting. Now every combo is going to act differently to any mod so to generalize and say that this is the end all be all of it is not what I am saying. Just that mufflers have there place on the street to appease the masses, and open headers and carefully tuned and selected exhaust pieces are best for all out performance (sans muffler)
1970 Barracuda project in the making!

Offline AussieMark

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Re: Uncapped headers
« Reply #19 on: September 26, 2016 - 04:10:10 am »
Take the mufflers off and go for a drive and let me know what you think, I have tried it on a lot of cars and trucks driving them with as much exhaust as we could fit at the shop and then drive them to the exhaust shop to be fitted up with a full system to me it is all noise and no power and on the way back it is heaps better. 4 stroke engines still need back pressure to operate exhaust valves will burn and leak and there is such a thing as over exhausting when the pipes are too large in diameter for the engine so no pipe at all must be even worst. Maybe a race engine that revs a lot higher then the normal engines I have tried are different but they still have to build the revs they can't idle at 5000 rpm I still don't get it.